This invention relates to a geometrically apertured protective splint device containing re-mouldable thermoplastic material that can be used as a composite splint material for immobilisation, bracing, casting, protection or support of limbs and body parts on humans and animals.
From here on in the term “device” will be used to denote the term geometrically apertured device containing re-mouldable thermoplastic material.
The term splint employed herein refers to an embodiment of the device in a sheet or a preformed sheet used for limb immobilisation, support and/or protection.
This invention relates to a splint device and to a composite material used for such.
Immobilisation of fractured or injured joints or limbs typically involves the process of restraining the joint or limb in place with a splint, cast, or brace. This is done to prevent the fractured/injured area from moving or being disturbed during the healing process.
Traditionally Plaster of Paris on fabric or gauze bandage has been used to form casts for the immobilisation of limbs. However Plaster of Paris has a number of disadvantages associated with it. For example Plaster of Paris is relatively heavy and bulky, has a slow setting time, cannot be reformed once set, possesses low impact resistance, and is susceptible to deterioration or damage once exposed to moisture thus making bathing and showering difficult. Additional concerns associated with the use of Plaster of Paris casting bandages are that they require a significant amount of time, usually 24 to 72 hours, to achieve their maximum strength, and that heat is generated from the exothermic setting reaction. Plaster of Paris also has poor radiopacity which prevents the continued monitoring of the limb during the healing process. In addition Plaster of Paris is substantially impervious to transmission of water vapour, such as perspiration. Thus Plaster of Paris traps moisture which can result in significant skin maceration.
One partial solution to improve breathability is the use of a thermoplastic mesh disclosed in U.S. Pat. No. 4,143,655, Custer et al. A negative drawback however with this method is the necessity to apply multiple layers of mesh to achieve adequate strength to support and protect body areas. Another drawback of this method is that the mesh needs to be trimmed in order to fit different body areas and this results in sharp edges that are formed due to trimming. Another disadvantage of this method is that underlying bandages, padding, dressings and gauzes can become wet because the material is usually heated using a hot water bath to soften the material to facilitate moulding. Moist dressings promote bacteria growth and can lead to discomfort and further complications.
It is usually prescribed that thermoplastic mesh and thermoplastic sheets with perforations are heated using a water bath. This will help to reduce the (unwanted) high tack characteristic associated with these materials which makes it otherwise difficult for the user to handle. However this means that these devices and materials are often wet when applied.
In the case of splints and casts it is important that devices and materials have sufficient strength to maintain correct alignment of fractured bones, or to restrict movement of a limb in order to promote healing, or to stabilise and help reduce swelling of injured limbs, or to protect a body area from impact and injury. In the case of fractured bones and where there is swelling or a risk of swelling it is an advantage if the devices or materials used have superior strength in the lateral direction along the limb to maintain firm alignment of the underlying fractured bone whilst it is a further advantage if the same devices or materials used have reduced strength and some slight flexibility around the circumferential direction of the limbs being covered in order that the device can be adjusted to compensate for swelling.
In cases where devices or materials are used to protect body parts from impact and injury it is important that the devices or materials have sufficient strength to withstand an impact and also be capable of transmitting/dissipating the force of the impact onto and across underlying padding or shock absorber materials to reduce or prevent injury to the underlying body part on humans and animals.
Those familiar in the art will recognise the importance of having breathable and open surfaces in devices and materials used for immobilisation, bracing, casting, protection or support of limbs and body parts on humans and animals in order to reduce skin maceration problems and clinical complications and to promote a reduction of healing times.
For wearer's comfort, minimisation of restrictions to natural body movements and to reduce recuperation times it is important that the weight of devices and materials used for immobilisation, bracing, casting and protection is kept to a minimum. Device design, volume of material used and material density are factors that influence the final weight of such devices.
We have discovered that three interdependent factors contribute significantly to the useful service performance of devices used for immobilisation, bracing, casting, protection or support of limbs and body parts on humans and animals.
These factors are:                The device has sufficient strength particularly in the lateral axis parallel to a limb        The device has breathable and open surfaces to facilitate drying and aeration        The volume of material used in the device is optimised for the intended device purpose        
We have combined a material with thermoplastic characteristics, and moulded profiled blanks containing geometric apertures to enable cost effective manufacture of devices that improve the useful service performance of devices used for immobilisation, bracing, casting, protection or support of limbs and body parts on humans and animals.
We herein disclose test techniques which produce numerical data showing the interdependent relationship of strength to surface openness as a function of the volume of material used, in optimised and non optimised devices.
Furthermore we disclose a most favourable Strength to Openness Index range whereby the relationship between the open surface area and strength of the revealed devices can be expressed in numerical format to show the superior properties of a geometrically apertured device consisting of a re-mouldable thermoplastic material also herein disclosed.